May you please elaborate how is your cell configured? Do you have a potentiostat/galvanostat or a power source and a multimeter? Do you have available a commercial or self-made reference electrode?
With that information we can provide an answer.You can do it simply with a reference electrode and a multimeter if your cell is running on an average power source.
I am using single-chamber membrane-free Microbial Electrolysis Cell (MEC) reactor for my experiment. I don't have potentiostat/galvanostat, i got a programmable power supply and a benchtop digital multimeter. Available a commercial Ag/AgCl reference electrode, RE-5B; BASi. I would like to know how to connect Ag/AgCl reference electrode in the electrical circuit?
This technical note from Gamry may help you. Basically you need to connect the multimeter in paralell to the portion of the system you want to study. Yet no current should flow through your reference electrode. Your reference electrode should be placed as close as possible to the working electrode you want to measure and just connect your multimeter to both (not un fused mode). If it is not clear please feel free to ask further.